Synchronous device for change-speed gears,especially for motor vehicles

ABSTRACT

A synchronous device for change-speed gears, especially for motor vehicles, wherein slotted correcting rings are under the influence of locking members for increasing the servo effect. During the synchronizing operation, the locking or arresting members are brought into pre-tensioned contact onto the correcting rings between sliding or shiftable stops. The inner surface of the correcting rings and/or the surfaces of the locking members operatively cooperating therewith are provided, at least in part, with a friction layer comprising a thin-walled coating of high friction coefficient material such as copper, titanium, molybdenum or the like.

United States Patent 11 1 Austen [11]" 3,744,604 July 10, 1973SYNCHRONOUS DEVICE FOR CHANGE-SPEED GEARS, ESPECIALLY FOR MOTOR VEHICLES[75] Inventor: Jiirg Austen, Weinsberg, Germany [73] Assignee: FirmaDr.-lng. h. c. F. Porsche KG,

Stuttgart-Zuffenhausen, Germany [22] Filed: Dec. 21, 1970 [21] Appl.No.: 100,172

[30] Foreign Application Priority Data Dec. 19, 1969 Germany P 19 63701.5

52 U.S. c1 192/53 c, 192/107 M 51 1111. C1. F16d 13/00 58 Field ofSearch 192/107 M, 107 R,

'192 107 T, 53 B, 53 c, 53 E [56] References Cited UNITED STATES PATENTS3,152,676 lO/l964'-Mand1ingeretal...i ..192/s3c 7 3,347,347 10/1967Hetmann.. ..192/107M 3,200,920 8/1965 Reich 192/53 C PrimaryExaminer-Charles J. Myhre Assistant Examiner-Randall HealdAttorney-Craig and 'Antonelli ABSTRACT A synchronous device forchange-speed gears, especially for motor vehicles, wherein slottedcorrecting rings are under the influence of locking members forincreasing the servo effect. During the synchronizing operation, thelocking or arresting members are brought into pre-tensioned contact ontothe correcting rings between sliding or shiftable stops. The inner surface of the correcting rings and/or the surfaces of the locking membersoperatively cooperating therewith are 7 1 provided, at least in part,with a friction layer comprising a thin-walled coating of high frictioncoefficient material such as'copper, titanium, molybdenum or the like.

9 Claims, 4 Drawing Figures PATENIEDJUHOIQYB 3.744504 sum 2 or 2 Inrenfaribqcr ausrerw BY bwiu M,M MU&

RTTORNEYS SYNCIIRONOUS DEVICE FOR CHANGE-SPEED GEARS, ESPECIALLY FORMOTOR VEHICLES BACKGROUND OF THE INVENTION The present invention relatesto a synchronous device for change-speed gears, especially for motorvehicles, and. more particularly, to a synchronous device in whichslotted correcting rings are under the influence of locking bodies whichincrease the servo action thereof and which, during the synchronousprocess are brought into pretensioned contact onto the correcting ringsbetween stops. V

In a synchronizing device of the aforementioned kind such as shown, forexample, in German Pat. 1,038,925, the arresting or looking bodiesv areconstructed as spring steel bands which exert a radial pressure to theinside of the correcting ring during the synchronous operation so thatit cannot be over-pressured by the shifting sleeve beforesynchronization is reached. The arresting or looking force exerted onthe correcting ring is dependent upon the shifting force exerted at theshifting sleeve and thereby limits the work effort by the driver. i t

SUMMARY OFTI'IE INVENTION It is the aim of the present invention toovercome the problems and disadvantages encountered in the prior artconstructions by the improvement of the arresting or looking actionduring the synchronizing operation.

It is a further aim of the present invention toincrease the arresting orlocking force of the synchronous device in order to obtain a stillshorter shifting time period.

The foregoing problems have been solved in accor dance with the presentinvention by providing a synchronous device, wherein the inner surfaceof the correcting rings and/or the surfaces of the arresting or lookingbodies cooperating therewith are provided, at

least over a portion thereof, with a friction layer.

Another advantageous feature of the present invention resides in thatthe friction layer is formed by a thinwalled coating utilizing amaterial having a high friction cooefficient such as, for example,titanium, copper, molybdenum or the like.

A further advantageous feature of the present invention resides in thatthe friction layer between the arresting or locking members and thecorrecting ring have about the same friction value as the frictionsurface at the circumference of the correcting rings serving for thesynchronizing work.

By employing the small relative movement between the looking orarresting members and the correcting ring during the synchronizingprocess in accordance with the present invention, the induced shiftingforce is transformed into a radial arresting or locking force whichslidingly holds the surfaces of the locking members and the correctingring against each other, the larger and more effective the frictionconnection or contact is of the surfaces of the locking members and thecorrecting ring. Through the gearing effect thereby created, theradially effective contact pressure of the correcting ring onto theshift sleeve is further increase so that the time for the equalizationof the rotative speed and under a shifting force which remains equal isfurther shortened.

In accordance with the present invention, it has been found thatthin-walled coatings, especially of titanium,

have been very successful as a friction layer between the contactsurfaces. It is to be understood, however, that copper alloys which areapplied galvanically or a molybdenum layer applied by the flame-sprayingmethod have also been used with relatively good success. Moreparticularly, favorable synchronizing values with sufficient surfacewearing like have been obtained by means of the present invention whenthe friction layer between the arresting or locking members and thecorrecting ring have about the same friction coefficient as the frictionsurface of the circumference of the correcting ring serving for thesynchronizing work.

BRIEF DESCRIPTION OF THE DRAWING These and further aims, features andadvantages of the present invention may become more apparent from thefollowing description when taken in conjunction with the accompanyingdrawing which shows, for purposes of illustration, an embodiment inaccordance with the present invention and wherein:

FIG. 1 is a partial cross-sectional, longitudinal view through thesynchronous device for the shifting sleeve gear of a motor vehicleincluding the locking members in accordance with the present invention;

FIG. 2 is a sectional view along line II-II ofFIG. 1;

FIG. 3 is an isolated view of the correcting rings of the synchronousdevice according to FIG. 1; and

FIG. 4 is a isolated view of the: locking or arresting membersassociated with the correcting ring of FIG. 3.

DETAILED DESCRIPTION OF THE DRAWING Referring now to the drawing and, inparticular, to FIG. 1, there is shown a partial view of the changespeedgear, wherein gears 2 and 3 are freely rotatably arranged on a driveshaft 1 but are not shiftable in a longitudinal direction thereof. Thegears 2, 3 are in constant engagement with gears not shown) on a furthergear shaft and are provided with clutch bodies 4, 5, respectively. Theclutch bodies 4, 5 are clutchable or engageable with a shifting sleeve 6which is axially movably held on webs Z of a shifting sleeve carriersupport 8. The shifting sleeve carrier support 8 is solidly connected orkeyed on the drive shaft 1 so as not to be freely rotatable and is alsofixed axially between the stop disks 9.

The head surfaces of teeth 10 of the shifting sleeve 6 operativelycooperate together with correcting rings 11 and 12 of the synchronousdevice, which correcting rings are arranged on the hub 13 of the clutchbodies 4 and 5 of ,the gears 2 and 3 which are to be shifted. Each ofthe correcting rings l1, 12 is provided with a centering surface 14 anda friction surface 15 which have a friction layer 16 of, for example,molybdenum as shown in FIG. 3. A nose .19 of a sliding stop pro trudesbetween the ends 17 and 18 of the correcting ring 11, and the slidingstop 20 is moveably held on the hub 13 of the respective clutch body ina circumferential direction. Locking or arresting members 22 and 23 inthe form of bands are arranged between the hub 13 and the inner surface21 of the correcting ring 11. The ends of the locking or arrestingmembers 22, 23 support themselves on a stop 24 which is held stationaryin the hub 13. The surfaces 25, 25 of the arresting or looking bands 22and 23 as shown in FIG. 4 operatively cooperate with the correcting ringand are provided with a coating 26 of, for example, titanium. Thecoating is of small thickness and may be applied by a conventionaladhesion process, such as, for example, flame spraying. In place of acomplete coating on the surface 25, however, a partial coating 26' isalso possible as shown on the right half of FIG. 4.

During shifting of a speed and depending on the selection of theshifting direction, the shifting sleeve 6 is axially shifted in relationto the shifting sleeve carrier support 8. If the shifting sleeve 6, asshown in FIG. 1 is moved to the left, the head surfaces of the shiftingteeth 10 will become friction-closed with the friction surface of thecorrecting ring 11, whereby the correcting ring 11 is taken along in therotational direction R as shown in FIG. 2. By means of the mounting ofthe end 17 of the correcting ring 11, the sliding stop 20 is pressed inthe same direction, so that the tension band and or locking member 23 istensioned against the stop member 24. During this process, a relativemovement between the inner surface 21 of the correcting ring 11 andsurface 25 takes place resulting in friction work which is effective onthe correcting ring in the form of a spreading force. If, through thefriction work between the friction surface 16 and the shifting sleeve,on one hand, and the arresting or locking band and the inner surface ofthe correcting ring, on the other hand, synchronism is obtained, thesynchronous device is relaxed or uncocked. Therefore, the shiftingsleeve 6 may be pressed over the correcting ring 11 and brought intoengagement with the clutch body 4 so as to complete the shiftingprocess.

.While I have shown and described one embodiment in accordance with thepresent invention, it is to be clearly understood that the same issusceptible of numerous changes and modifications as will be apparent toone skilled in the art. Forexample, the inner surface of the correctingrings may be provided with a friction coating 27, as shown in FIG. 3 bydot-dashed lines, in leiu of a friction coating on the arresting orlocking bands. If need be for large synchronous devices, both surfacesworking together can be provided with a friction layer or coating. I,therefore, do not wish to be limited to the details shown and describedherein but intend to cover all such changes and modifications as areencompassed by the scope of the present invention.

What is claimed is:

l. Synchronous device arrangement for changespeed gears of the type usedon motor vehicles which include a rotating drive shaft and an axiallymovable shifting sleeve arranged around said drive shaft for selectiveinterengagement with at least one gear positioned around said driveshaft; said arrangement comprising: a slotted correcting ring positionedcircumferentially around said drive shaft between said sleeve and saidgear, said ring having a radially outwardly facing friction surface forfrictionally engaging radially in-' wardly facing gear teeth provided onsaid. shifting sleeve, locking band means positioned radially inwardlyof said ring, said locking band means having radially outwardly facingfriction surface means for engaging a radially inwardly facing frictionsurface provided on said ring, circumferentially movable stop meanspositioned between the ends of the ring for transferring circumferentialmovement forces from said ring to said locking band means, andcircumferentially fixed stop means positioned on said shaft for limitingcircumferential movement of said locking band means, wherein allsynchronizing forces resulting from relative circumferential movementsbetween said sleeve and said one gear during the synchronizing processare absorbed by the respective frictional sliding engagement betweensaid radially outwardly facing surface of said ring and said teeth onsaid sleeve and between said radially inwardly facing surface of saidring and said radially outwardly facing friction surface means of saidlocking band means, wherein at least one of the two surfaces comprisingthe radially inwardly facing surface of said ring and the radiallyoutwardly facing surface means of said locking band means is providedwith a friction layer for absorbing and transferring away the excessiveheat generated during the synchronizing process and for enhancing thefrictional engagement of the respective two surfaces, and wherein thefriction layer is constructed such that the coefficient of friction forthe two surfaces on said ring and locking band means is approximatelythe sameas the coefficient of friction for the surfaces on said ring andsaid sleeve teeth.

2. A arrangement according to claim 1, wherein the friction layer is athin-walled coating of high friction coefficient material.

3. An arrangement according to claim 2, wherein the high frictioncoefficient material is selected from the group consisting of titanium,molybdenum and copper.

4. An arrangement according to claim 1, wherein both of said twosurfaces are provided with a friction layer.

5. An arrangement according to claim 4, wherein the friction layer is athin-walled coating of high friction coefficient material.

6. An arrangement according to claim 5, wherein the high frictioncoefficient material is selected from the group consisting of titanium,molybdenum and copper.

7. An arrangement according to claim 2, wherein the high frictioncoefficient material is titanium.

8. An arrangement according to claim 2, wherein the high frictioncoefficient material is molybdenum.

9. An arrangement according to claim 2, wherein the high frictioncoefficient material is copper.

1. Synchronous device arrangement for change-speed gears of the typeused on motor vehicles which include a rotating drive shaft and anaxially movable shifting sleeve arranged around said drive shaft forselective interengagement with at least one gear positioned around saiddrive shaft; said arrangement comprising: a slotted correcting ringpositioned circumferentially around said drive shaft between said sleeveand said gear, said ring having a radially outwardly facing frictionsurface for frictionally engaging radially inwardly facing gear teethprovided on said shifting sleeve, locking band means positioned radiallyinwardly of said ring, said locking band means having radially outwardlyfacing friction surface means for engaging a radially inwardly facingfriction surface provided on said ring, circumferentially movable stopmeans positioned between the ends of the ring for transferringcircumferential movement forces from said ring to said locking bandmeans, and circumferentially fixed stop means positioned on said shaftfor limiting circumferential movement of said locking band means,wherein all synchronizing forces resulting from relative circumferentialmovements between said sleeve and said one gear during the synchronizingprocess are absorbed by the respective frictional sliding engagementbetween said radially outwardly facing surface of said ring and saidteeth on said sleeve and between said radially inwardly facing surfaceof said ring and said radially outwardly facing friction surface meansof said locking band means, wherein at least one of the two surfacescomprising the radially inwardly facing surface of said ring and theradially outwardly facing surface means of said locking band means isprovided with a friction layer for absorbing and transferring away theexcessive heat generated during the synchronizing process and forenhancing the frictional engagement of the respective two surfaces, andwherein the friction layer is constructed such that the coefficient offriction for the two surfaces on said ring and locking band means isapproximately the same as the coefficient of friction for the surfaceson said ring and said sleeve teeth.
 2. An arrangement according to claim1, wherein the friction layer is a thin-walled coating of high frictioncoefficient material.
 3. An arrangement according to claim 2, whereinthe high friction coefficient material is selected from the groupconsisting of titanium, molybdenum and copper.
 4. An arrangementaccording to claim 1, wherein both of said two surfaces are providedwith a friction layer.
 5. An arrangement according to claim 4, whereinthe friction layer is a thin-walled coating of high friction coefficientmaterial.
 6. An arrangement according to claim 5, wherein the highfriction coefficient material is selected from the group consisting oftitanium, molybdenum and copper.
 7. An arrangement according to claim 2,wherein the high friction coefficient material is titanium.
 8. Anarrangement according to claim 2, wherein the high friction coefficientmaterial is molybdenum.
 9. An arrangement according to claim 2, whereinthe high friction coefficient material is copper.